This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The early recognition of severe hemorrhage is a key factor towards reducing mortality and morbidity from battlefield insults. Although near-infrared (NIR) instruments have shown promise in recognizing hemorrhage, specific confounding factors must be solved to be reliable in early hemorrhage. Our hypothesis is that these confounding factors can be eliminated by proper light-tissue interaction modeling (frequency-domain photon migration), and by increasing spectral (1000 wavelengths) and temporal (200 ms) bandwidth. The objective of this proposal is to provide a compact point-of-care NIR instrument that is capable of quantitatively detecting early hemorrhage and monitoring therapeutic interventions. Our proposal features collaboration between (1) a leading biomedical technology company (ISS, Inc., Champaign, IL) that produces state-of-the-art NIR tissue oximeters, operates production facilities and has FDA submission experience, and (2) a university research team (Beckman Laser Institute, UC Irvine), with tissue optics experts who have experience in the assessment of traumatic injury via NIR optical methods. The existing ISS oximeter will be modified to increase information content that will solve the confounding factors. At the conclusion of Phase I, we will provide a unique NIR instrument that will be available for comprehensive validation and optimization studies (Phase II) and subsequent commercial miniaturization (Phase III).